Intra-specific interactions disrupted the nutrient dynamics and multifactorial responses (drought and salinity) in Dalbergia odorifera in a pure planting system.

Abstract

Woody species associated with coastal shelter forest ecosystems often face multiple types of stress, including drought and salinity. The impact of these abiotic stresses when they occur individually and in combination can have substantial impacts on tree species distribution and survival. The effect of stressors can also be influenced by intra-specific biotic factors. The present study investigated the nutrient dynamics and eco-physiological responses of Dalbergia odorifera T. C. Chen in response to these stressors under three different pure planting densities. The results showed that exposure to either salinity or drought stress led to a significant reduction in biomass and photosynthesis and an increase in oxidative stress markers. However, the most severe effects were observed under combined stress conditions. The adverse effects of these stressors were exacerbated as planting density increased, highlighting the role of inter-plant competition in stress response. Although increasing plant density did not consistently affect the nutrient contents among different organs, higher densities tended to exacerbate nutrient stress, especially for sodium and potassium, indicating competitive interactions or altered uptake dynamics. Combined stress (drought, salinity and planting density) conditions generally result in synergistic effects in several key physiological parameters, leading to more severe impacts on plant physiology than individual stresses. The findings have implications for managing this woody forest species in forestry and agricultural backdrops, particularly under extreme weather conditions.